Battery-separator and process of making the same.



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mmns ml SKENNER, or rmnannnrma, rnnnsYLvAmA, assrenonTo PHILADEL- PHIA sTo'nAGE BATTERY comrm,

CORPORATION 01 IA.

ea, PHILADELPHIA. PENNSYLVANIA, A

BATTERY-SEPARATOB Am) rndjcnsls or MAKING THE No Drawing.

' certain Improvement in Battery-Separators and Processes of Making the Same,of which the following is a specification.

One object of my invention is to provide a relatively simple and inexpensive method of treating sheets of wood to fit them for use as separators for the plates of secondary or storage batteries, the process being such that'the separators produced possess in .a

high degree the qualities required of them;

i. e., their internal resistance'is low, their strength under working conditions m a battery is'high, and they contain nothing which underordinary conditions will injuriously resistance is relatively high. As a result of.

act upon the materials of which the battery plates are composed.

My invention also contemplates the pro-' vision of a battery above characteristics. 4

I have discovered that of .the ordinary woods available for use as battery separaseparator having the tors, certain of them, such as white pine,

Douglas fir, and the common species of cedarfpossess to a high degree certain of the qualities desired, for they contain practically negligible amounts of material which lates, such as however, the objection that their internal my experiments I have found that the presence of the small quantity. of acetic acid forming compounds in the white pine and other wood separators hereinafter specified is beneficial to the negative battery plates rather than harmful, so that in preparing the wood for use as separators in sheet'or other form I subject it to a treatment which,-

while having practically no efiect' upon these compounds, servesto materially lower its internal resistance. Further, the treatment does not remove lignone to an injuri- Speciflcation of Letters Iatent.

Patented Mar. 2, 1915.

Application filed May 13, 1914. Serial No. 838,406.

Y period of from 24 to 48 hours, more or less,

although, in some cases, I may boil them'in water under pressure up to 80 pounds to the square inch for a period of from five to ten hours, although this time will vary with y the wood and the pressure employed. Again,

I may obtain thedesired result by subjecting the wood to the action of steam under pressure for a period of twelve hours.,morc or less. By. any of the above described methods of treatment there is removed from the wood a sufiicient'amount of its resinous and possibly other insulating. constituents, with such a swelling and softening, as will lower its internal resistance tosuch an extent as to fit it for use as a battery separator. At the same time, the acetic acid forming compounds remain practically unafi'ected. I have also found that the internal resistance of the wood may be lowered to the desired point without removing the acetic acid forming compounds, by treating it with a solvent other than waterwhich removes only the resinous constituents, and if alcohol be the substance employed, I immerse the wood in a body of this liquid, which may be heated to a temperature slightly below its boiling point, for-such a length of time as is necessary to-attain the desired end. Obviously, the solvent may be employed under pressure in a closed vessel, as might be ad- 2. The process of preparing battery sepainsulating compounds that its resistance is 10 rators which consists in boiling the wood of relatively low.. I coniferous trees in water for a period of In testimony whereof, I have signed my from 24 to 48 hours. name to this specification, in the presence of 3. A battery separator produced by the two subscribing witnesses. herein described process which consists of JAMES M. SKINNER. coniferous wood containing a relatively Witnesses: 7 small percentage of acetic acid forming com- WILLIAM E. BRADLEY, pounds and including such an amount of Win. A. BARR. 

